Medical fluid therapy flow balancing and synchronization method and apparatus

ABSTRACT

A medical fluid therapy method includes: (a) establishing a communication link between a kidney dialysis/blood treatment machine and at least one remote pump controller; (b) using the link to synchronize operation of at least one pump housed integrally with the machine with at least one pump located remotely from the machine; (c) enabling an operator to enter a net fluid transfer amount; and (d) controlling the pumps to at least substantially achieve the entered amount.

PRIORITY CLAIM

This application claims priority to and the benefit as a divisionalapplication of U.S. patent application “MEDICAL FLUID THERAPY FLOWBALANCING AND SYNCHRONIZATION SYSTEM,” Ser. No. 10/685,724, filed Oct.15, 2003.

BACKGROUND

The present invention relates generally to medical treatments. Morespecifically, the present invention relates to the synchronization ofvarious fluids used to treat renal failure, fluid overload, congestiveheart failure, drug overdoses, poisonings, immune disorders, sepsisand/or acid balance imbalances.

Due to disease, insult or other causes, a person's renal system canfail. In renal failure of any cause, there are several physiologicalderangements. The balance of water, minerals and the excretion of dailymetabolic load are reduced or no longer possible in renal failure.During renal failure, toxic end products of nitrogen metabolism (e.g.,urea, creatinine, uric acid, and others) can accumulate in blood andtissues.

Kidney failure and reduced kidney function have been treated withdialysis. Dialysis removes waste, toxins and excess water from the bodythat would otherwise have been removed by normal functioning kidneys.Dialysis treatment for replacement of kidney functions is critical tomany people because the treatment is life sustaining. One who has failedkidneys could not continue to live without replacing at least thefiltration functions of the kidneys.

Hemodialysis (“HD”), hemofiltration, hemodiafiltration and peritonealdialysis are types of dialysis therapies generally used to treat loss ofkidney function. Peritoneal dialysis utilizes a sterile dialysissolution, or “dialysate”, which is infused into a patient's peritonealcavity and into contact with the patient's peritoneal membrane. Waste,toxins and excess water pass from the patient's bloodstream through theperitoneal membrane and into the dialysate. The transfer of waste,toxins, and excess water from the bloodstream into the dialysate occursdue to diffusion and osmosis during a dwell period as an osmotic agentin the dialysate creates an osmotic gradient across the membrane. Thespent dialysate is later drained from the patient's peritoneal cavity toremove the waste, toxins and excess water from the patient.

Hemodialysis treatment removes waste, toxins and excess water directlyfrom the patient's blood. The patient is connected to a hemodialysismachine and the patient's blood is pumped through the machine. Needlesor catheters are inserted into the patient's veins and arteries tocreate a blood flow path to and from the hemodialysis machine. As bloodpasses through a dialyzer in the hemodialysis machine, the dialyzerremoves the waste, toxins and excess water from the patient's blood andreturns the cleansed blood back to the patient. A large amount ofdialysate, for example about ninety to one hundred twenty liters, isused by most hemodialysis machines to dialyze the blood during a singlehemodialysis therapy. Spent dialysate is discarded. Hemodialysistreatment lasts several hours and is generally performed in a treatmentcenter about three times per week.

Another type of renal failure therapy is referred to generally ascontinuous renal replacement therapy (“CRRT”). While HD primarily reliesupon diffusion to remove unwanted solutes, CRRT is a collection ofsubtherapies that utilize diffusion and/or convection in order togenerate solute clearance, balance pH and fluid removal. During one typeof CRRT, blood flows through a filter, such that a transmembranepressure gradient between the blood compartment and the ultrafiltratecompartment causes plasma water to be filtered across the highlypermeable membrane. As the water crosses the membrane, it can convectsmall and large molecules across the membrane and thus cleanse theblood.

CRRT has certain advantages relative to traditional dialysis therapies.A foremost advantage is the potential to effectively avoid, or at leastminimize, cardiovascular instability. CRRT, in general, is a slow andcontinuous therapy that does not include rapid shifts in blood volumeand electrolyte concentration due to the removal of metabolic productsfrom blood as compared to intermittent forms of dialysis therapy, suchas hemodialysis. Examples of continuous renal replacement therapiesinclude continuous arteriovenous hemofiltration, continuousarteriovenous hemodialysis, continuous arteriovenous hemodiafiltration,continuous venovenous hemofiltration, continuous venovenoushemodiafiltration, continuous venovenous hemodialysis, slow continuousultrafiltration, hemoperfusion and continuous ultrafiltration withperiodic intermittent hemodialysis.

Hemofiltration, one type of CRRT, is an effective convection-based bloodcleansing technique. Blood access can be venovenous or arteriovenous. Asblood flows through the hemofilter, a transmembrane pressure gradientbetween the blood compartment and the ultrafiltrate compartment causesplasma water to be filtered across the highly permeable membrane. As thewater crosses the membrane, it convects small and large molecules acrossthe membrane and thus cleanses the blood. A large amount of plasma wateris eliminated by filtration. Therefore, in order to keep the body waterbalanced, fluid must be substituted continuously by a balancedelectrolyte solution (replacement or substitution fluid) infusedintravenously. This substitution fluid can be infused either into thearterial blood line leading to the hemofilter (predilution), into thevenous blood line leaving the hemofilter (postdilution) or both. Anothertype of therapy, hemodiafiltration, combines the diffusion andconvective cleansing modes of hemodialysis and hemofiltration. Thepresent invention expressly applies to each of the therapies mentionedherein including, additionally TPE, cytopheresis and hemoperfusion.

Each of the renal failure therapies involves the flow and control ofmultiple fluids. Some commercially available replacement or substitutionfluids, for example, are lactate-based solutions. In certain instances,such as with patients with multiple organ failure, the use of thephysiological buffer bicarbonate is preferred over lactate. It is commonpractice to manually prepare solutions buffered with bicarbonateextemporaneously. This is typically carried out by adding the preparedbicarbonate solution to an existing injectable quality solution to formthe bicarbonate-based solution prior to administration to the patient.For example, it is known to add bicarbonate to an acidic electrolyteconcentrate solution, which is in direct contact with administrationtubing connected to the patient prior to administration thereof to thepatient. It is also common practice to manually inject otherelectrolytes, such as potassium chloride, directly and separately intothe bicarbonate-based solution prior to administration. The physicalhandling of the fluids can become tedious and time-consuming.

It should be appreciated that for each of the above-described types ofrenal failure therapies, transferring and monitoring the flowrate andthe total volume of fluid delivered for multiple types of fluids as wellas adhering to certain therapy restrictions (e.g., a first fluid must beflowing to or from the patient to enable a second fluid to flow) eachcreate a control dilemma. Managing a patient's total fluid balance ofteninvolves obtaining the patient's prescribed net fluid loss or gain andmanually summing various fluid inputs and fluid outputs to arrive at anecessary removal rate, which is then entered into a renal failuretherapy machine, such as a dialysis machine or a CRRT machine. Forexample, if a patient is prescribed to have a net fluid loss(ultrafiltrate removal above and beyond patient fluid input but takinginto account other sources of fluid output) of two hundred milliliters(“ml”) per hour (“hr”), is receiving one hundred ml/hr of fluid via anintravenous (“IV”) pump and has fifty ml/hr of urine output, theoperator would have to calculate and instruct the renal failure therapymachine to remove two hundred fifty ml/hr of ultrafiltrate above andbeyond replacement of substitution fluid that is being delivered by theCRRT or dialysis machine, so that the net total volume of fluid(removed) over the hour is two hundred ml.

The above example used only one IV fluid. It is possible however to havemultiple IV or administration fluid inputs, making the above-describedprocess even more involved and error prone. A need therefore exists toprovide an improved system for calculating, balancing, synchronizing andcontrolling the delivery of multiple fluids in a renal failure therapy.

SUMMARY

The present invention provides a system, apparatus and method that allowexternal infusion, IV or administration pumps to be synchronized withthe internal pumps of a medical fluid therapy machine. The systemreduces the time and effort needed to calculate, set-up, enter andmaintain flowrates of various fluids, maintained internally orexternally with respect to the medical fluid therapy machine. The systemalso automatically follows therapy requirements, for example, arequirement that one pump/fluid be running/flowing for anotherpump/fluid to be enabled to run/flow. The system further automaticallyadjusts for variations in flowrate of one fluid with respect to another.For example, filtrate/output pump internal to the machine may increaseor decrease in response to the flowrate or output rate of a manuallyentered value of an external pump or measuring device. In short, thesystem provides a more “hands-off”, safe and effective method andapparatus for medical fluid therapy delivery and removal.

“Medical fluid therapy” as used herein includes, but is not limited toperitoneal dialysis, hemodialysis, hemofiltration, hemodiafiltration,therapeutic plasma exchange, cytopheresis, hemoperfusion and continuousrenal replacement therapy (wherein CRRT includes continuousarteriovenous hemofiltration, continuous arteriovenoushemodiafiltration, continuous arteriovenous hemodialysis, continuousvenovenous hemofiltration, continuous venovenous hemodialysis,continuous venovenous hemodiafiltration, slow continuousultrafiltration, and continuous ultrafiltration with periodicintermittent hemodialysis) and any combination thereof. The inventionincludes a communication system in which a medical fluid therapy machinesets, monitors, retrieves information from and controls pump flowratesfor pumps both integral and external to the machine. The system therebyachieves a desired positive, neutral or negative net volume of fluidflow to or from a patient over a given period of time.

The system enables an operator to enter, retrieve and/or store initialsettings for the pumps (integral and/or external), wherein one or moreof the pumps can be dependent upon the operation of one or more otherpumps. For example, the operator could set a particular externalinfusion pump to synchronize with the internal blood pump. In such acase, the medical fluid therapy machine would, for example, command theinfusion pump to run when the blood pump is running and to pause whenthe blood pump stops running.

The system also enables the operator to enter a desired net loss or gainamount, wherein the system automatically calculates and adjusts thevarious internal and external input and/or output flowrates associatedwith the therapy to achieve the entered net loss or gain of fluid. Thesystem facilitates communication between pumps and sensors locatedinside the medical fluid therapy machine with pumps and measuringdevices located external to such machine.

The system reduces substantially the amount of manual flowratecalculations that have heretofore been required. Further, instead ofrequiring the operator to manually set and inject or infuse one or moreadministration fluids, the system automatically sets and controls suchinjection/infusion. Moreover, during therapy the system can sense theactual amount of fluids flowed and compare same to the required amountand adjust the flowrates of the fluids accordingly and “on the fly” orsubstantially “on the fly.”

The system includes a number of modes of communication for allowing theexternal input/output devices to share information with the medicalfluid therapy machine, including wired (e.g., fiber optic cable) orwireless modes (e.g., RF signal) of communication. The machinecommunicates with the external input/output devices to communicate orretrieve information or send commands, such as: device on, device off,start pump, stop pump, pump rate, volume to be infused, clear rateinfused/removed, name of drug/solution being infused/removed andconcentration of drug/solution being infused/removed, etc.

The fluids balanced and controlled by the system of the presentinvention vary depending upon the patient's needs and upon on themedical therapy used. In the case of diffusive therapies, a dialysatewill be used to absorb toxins and other waste materials. In the case ofconvective therapies, an infusate or replacement fluid will be used.Each type of therapy is associated with its own set of IV oradministration fluids. A patient undergoing renal therapy may also bereceiving medication or infusions, such as heparin, calcium, magnesium,total parenteral nutrition (“TPN”) or vasoactive drugs such asdobutamine, dopamine, nitroglycerin, etc. While those medications aretypically stored and pumped by an outside pumping device, an internalpumping device may alternatively pump such medications.

An anticoagulant, such as heparin or citrate, could additionally bestored and pumped from an external or internal pump or storage device.The ability to synchronize anticoagulants, and in particular citrate, tothe blood pump, is critical. Setting the input of citrate to besynchronized with or to follow variations in blood flowrate and havingthe ability to balance the flow of citrate to a prescribed setting isparticularly advantageous.

The system uses the controller of the machine to control all fluids,internal or external, via a communication link to a remote controllerassociated with each of the external pumps. The system also retrievesvolumes delivered or rates of administration by external devices andaddresses those fluids with respect to the internal fluid balancingmonitored and controlled by the system to achieve the overall desiredpatient fluid balance.

It is therefore an advantage of the present invention to provide animproved medical fluid therapy control system, apparatus and method.

It is another advantage of the present invention to streamline the fluidflow control for a medical fluid therapy, such as peritoneal dialysis,hemodialysis, continuous arteriovenous hemofiltration, continuousarteriovenous hemodialysis, continuous arteriovenous hemodiafiltration,continuous venovenous hemofiltration, continuous venovenoushemodialysis, continuous venovenous hemodiafiltration, slow continuousultrafiltration, hemoperfusion, continuous ultrafiltration with periodicintermittent hemodialysis, therapeutic plasma exchange, cytophersis andany combination thereof.

It is a further advantage of the present invention to simplify thestart-up of a medical fluid therapy.

It is yet another advantage of the present invention to simplify thefluid flow maintenance of a medical fluid therapy.

It is yet a further advantage of the present invention to improve theflow delivery accuracy of a medical fluid therapy.

It is still another advantage of the present invention to reduce thepossibility for error in a medical fluid therapy.

Moreover, it is an advantage of the present invention to increase theflexibility of a medical fluid therapy with respect to adjustingflowrates on the fly and over multiple therapy sessions or to adjust theflowrates of one or more pump(s) in response to the rate of input oroutput of one or more fluid delivery or output measuring device(s).

Yet another advantage of the present invention is to balance andsynchronize the flowrate of an anticoagulant such as citrate.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a medical fluid therapy machine andvarious input/output devices located externally from the machine.

FIG. 2 is a schematic illustration of one embodiment of the pumpsynchronization system of the present invention, which shows asimplified electrical configuration thereof.

FIG. 3 illustrates one embodiment of a flow schematic of the presentinvention showing the operation of various pumps located internally andexternally with respect to a medical fluid therapy machine.

FIG. 4 is an input screen of a graphical user interface (“GUI”)operating with the medical fluid therapy machine showing theinterrelation between and control of various pumps controlled by thesynchronization network of the present invention.

FIG. 5 is an additional input screen of the GUI illustrating a flowcalculation that is made automatically by the system of the presentinvention.

DETAILED DESCRIPTION

The present invention is useful for medical fluid therapies, includingbut not limited to peritoneal dialysis, hemodialysis and CRRT (whereinCRRT includes continuous arteriovenous hemofiltration, continuousarteriovenous hemodialysis, continuous arteriovenous hemodiafiltration,continuous venovenous hemofiltration, continuous venovenoushemodialysis, continuous venovenous hemodiafiltration, slow continuousultrafiltration, hemoperfusion, therapeutic plasma exchange,cytopheresis, continuous ultrafiltration with periodic intermittenthemodialysis), fluid overloads, congestive heart failure, drugoverdoses, poisonings, immune disorders, sepsis, acid imbalances and anycombination thereof. The invention includes a network that, for any ofthe above therapies, enables pumps external to a main therapy machine tobe synchronized and controlled automatically with pumps providedintegrally with the machine. The system reduces the setup timeassociated with competing systems, automatically follows therapyrequirements, automatically adjusts for variations in flowrate of onefluid with respect to another and in general provides a safe andeffective method and apparatus for controlling a renal failure therapy.

Referring now to the figures and in particular to FIG. 1, asynchronization system or network 10 is illustrated. The system ornetwork 10 encompasses a medical fluid therapy (“MFT”) machine 20 andone or more external input/output devices 30, 40 and 50. MFT machine 20can for example be a hemofiltration machine, however, machine 20alternatively performs any of the medical fluid therapies describedabove or combinations thereof.

MFT machine 20 includes a controller, which is described in more detailbelow. That controller communicates with external input/output devices30, 40 and 50 via communication links 100. Communication links 100, inone embodiment, are hard-wired or a cabled connections, such aselectrical cables, data lines, analog or digital signals, local or widearea links, Internet links, or fiber optic links. In another embodiment,the communication links are wireless, such as a remote frequency (“RF”)links, ultrasonic links, photoelectric links, microwave links or thelike. Combinations of the above different methods of communication arealso contemplated.

As shown in more detail below, MFT machine 20 includes a multitude ofonboard or integral pumps, which each pump a different fluid. Externaldevices 30, 40 and 50 may be any type of device common to medical fluidtherapies, some of which are described in more detail below. Each ofthose devices includes, in one embodiment, a separate pump, which isconnected to either a source of fluid or a drainage container or outlet.Each of the devices 30, 40 and 50 also includes a microprocessor orother type of controller that is able to: (i) receive a command from MFTmachine 20 and send a status signal back to the MFT machine 20.

MFT machine 20 and the external input/output devices 30, 40 and 50 each,in one embodiment, include an address that distinguishes MFT machine 20from other such machines and external input/output devices 30, 40 and 50from other like devices. The addresses designate the pumps of the MFTmachine 20 and of the external input/output devices 30, 40 and 50 to beassociated with a specific patient that is undergoing hemofiltrationtherapy. The addresses prevent miscommunication between multiple MFTmachines 20 and associated input/output devices 30, 40 and 50 ifmultiple therapies are taking place simultaneously, for example, in atreatment center. The potential for miscommunication exists especiallywith wireless communication between the machine 20 and the externalinput/output devices. Such potential for miscommunication could alsooccur if, for example, the network enables one of a plurality ofcomputers located remotely from the MFT machine 20 to be used tosynchronize with multiple internal and external pumps of the therapy.Further, it is possible that one or more remote administration pumps isfluidly coupled to multiple MFT machines 20 or to multiple patients. Insuch a case, the controller for the administration pump needs to knowthe address of the MFT machine 20 needing fluid to be added or removed.

As illustrated, MFT machine 20 includes a housing 25 that houses themajor components of the machine, such as a blood pump, dialysate orreplacement fluid pump, a hemofilter/dialyzer, other onboard pumps andother components, such as, pressure sensors, air detectors, flow metersand the like. MFT machine 20 also includes a graphical user interface(“GUI”) 60, which enables the operator to run the MFT machine. GUI 60 isdiscussed in more detail below in connection with FIGS. 4 and 5.

In general, the GUI 60 operates with one or more microprocessors, whichcan be housed either inside GUI 60 or housing 25. Although GUI 60 isshown connected to housing 25, it is also possible that GUI 60 islocated on an external PC, which is connected to housing 25 via acomputer cable, such as a serial or parallel data transmission cable.The remote GUI 60 enables system 10 in one embodiment to be commandedthrough a central computer, which communicates and operates with aplurality of different MFT machine housings 25. In still a furtheralternative embodiment, the flow components within housing 25 as well asthe pumps of external input/output devices 30, 40 and 50 communicatewith GUI 60 over a local area network (“LAN”) or wide area network(“WAN”), such as the Internet. It is therefore possible for an operatorto control (send and receive commands/feedback) via a remote GUI 60 theoperation of the MFT machine 20 and the external input/output devices30, 40 and 50 for a patient who is at home.

As illustrated by rolling frame 22, MFT device 20 can be moved ororiented to a position that is convenient for operation. Additionally,MFT machine 20 includes various exterior apparatus 24, which are commonto MFT machines generally. Further, MFT machine 20 includes scales 26and 28 that enable the weight and thus the volume of one or more fluids,such as dialysate, replacement fluids or collected urine, to bedetermined. For instance, scale 26 is used in one implementation tomonitor the substitution fluid/dialysate flow, while scale 28 is used tomonitor the flow of ultrafiltrate.

Referring now to FIG. 2, a schematic electrical diagram is shown for themachine 20 of the pump synchronization system 10 of the presentinvention. The schematic includes the housing 25 of MFT machine 20discussed above in connection with FIG. 1. MFT machine 20 includes inhousing 25 a plurality of different pumps. In the illustratedembodiment, the MFT machine 20 houses a blood pump 112, a substitutionpump 114, a dialysate pump 116, a filtrate pump 118 and an anticoagulantpump 120 (e.g., for hemodiafiltration that uses both diffusive andconnective clearance modes). Each of the above-described pumps is commonto an MFT machine. Blood pump 112 pumps blood from a patient through afilter, such as a dialyzer or hemofilter, and back to the patient. Thesubstitution pump 114 pumps replacement fluid directly into thepatient's blood flow line either prior to or after a dialyzer orhemofilter. As stated above, hemofiltration is a convective process thatadds injectable quality fluid directly to the patient's blood, while ahemofilter removes ultrafiltrate from the patient's blood. In essence,hemofiltration exchanges the waste from the patient's blood directlywith an injectable quality solution such as a sterile solution.

FIG. 2 also illustrates a dialysate pump 116. Dialysate pump 116 isprovided typically in hemodialysis, but can also be used as illustratedin combination with hemofiltration (e.g., for hemodiafiltration).Dialysate pump 116 pumps dialysate into one end of a dialyzer. Thatdialysate absorbs waste flowing across membrane walls within thedialyzer, such as, sodium, potassium, phosphate, creatinin. Dialysatepump 116 therefore performs a similar function as the substitution pump114 in that both pumps pump an injectable quality biologicallycompatible fluid into either direct contact or transmembrane contactwith at least the waste components of patient's blood.

In either situation, whether a dialyzer or a hemofilter is used, afiltrate pump 118 is employed to remove ultrafiltrate from the patient'sblood. That is, whether a hemofilter or a dialyzer is employed, thefiltrate pump 118 is used to pull fluid from one of those devices toremove waste products and excess liquid from the patient's blood.

Anticoagulant or syringe pump 120 operates in a similar manner tosubstitution pump 114 to supply an anticoagulant to the patient's bloodflow line directly. Anticoagulant pump 120 is alternatively locatedexternal to machine 20 and communicates with controller 70 via a link100. For purposes of the present invention it does not matter whichpumps are located internal or external to machine 20 as long as a modeof communication exists via either internal wiring or an external link100.

In the illustrated embodiment, tachometers or flowmeters 122 to 130 areprovided and operate with pumps 112 to 120, respectively. Tachometers122 to 130 are of any type known to those of skill in the art to monitorthe pumps, which are accurate and non-invasive. Tachometers 122 to 130are placed adjacent to or in relatively direct fluid communication withlines leading directly to or from pumps 112 to 120. Feedback fromtachometers 122 to 130 for pumps 112 to 120, respectively, is sentelectronically to a controller 70. The pumps 112 to 120 are also eachconnected to or in communication with the controller 70, which in theillustrated embodiment is also housed within housing 25. Controller 70is also operably connected to the GUI 60.

FIG. 2 illustrates that the filtrate pump 118 also operates with ascale, such as scale 28, which produces a weight or mass signal that issent electronically to controller 70. Furthermore, substitution pump 114and dialysate pump 116 also operate with a shared scale, such as scale26, which produces a weight or mass signal that is sent electronicallyto controller 70. Other scale arrangements are possible. FIG. 2illustrates that an electrical or signal type communication furtherexists between each of the external pumps 32, 42 and 52 and controller70.

As illustrated, controller 70 is a multiprocessor type controller in oneembodiment. That is, controller 70 includes a first processor 72, orcontrol processor, which communicates with the pumps (pump controllers)to send and receive information to and from the pumps. Processor 72 alsocommunicates with other devices located within MFT machine 20, such asthe pressure sensors, temperature sensors, concentration sensors, airdetectors, blood detectors and the like. Control processor 72 operatesfurther with each of the other electrical components of machine 20, suchas lights, audio outputs, switches, etc.

Control processor 72 communicates with a second or safety processor 74,which in turn communicates with each of the pumps 112 to 120. Safetyprocessor or protective processor 74 monitors the pumps 112 to 120 forerror conditions, such as, communication loss, framing errors, invalidpacket format, data errors and the like. Safety processor 74 receivesstatus and parameter information from pumps 112 to 120 to ensure thatthe pumps and each of the fluids pumped thereby are operating withinpredefined safety limits. Safety processor 74 in turn handshakes withcontrol processor 72.

While controller 70 is shown having two processors 72 and 74 working incooperation, it is possible that controller 70 includes additionalprocessors. For example, controller 70 in an alternative embodimentincludes an additional supervisory processor that runs delegateprocessors, such as processors 72 and 74. A separate processor is alsoprovided in one embodiment to operate GUI 60. That processor can, forexample, run software that enables the machine 20 to be controlled overa network, such as the Internet. In the illustrated embodiment, GUI 60communicates with both processors 72 and 74 of controller 70. It is alsopossible that controller 70 includes a single processor operating bothindependent control and safety tasks.

Control processor 72 also communicates via links 100 (including each ofthe alternatives for links 100 described above) with a plurality ofexternal input/output pumps/controllers 32, 42 and 52. Pumps/controllers32, 42 and 52 are provided, for example, within external input/outputdevices 30, 40 and 50, shown above in connection with FIG. 1.

Control processor 72, located within housing 25 of machine 20 asillustrated, controls pumps and pump controllers 112 to 120 that arehoused within machine 20 as well as pumps/controllers 32, 42 and 52located external to machine 20. Processor 72 sends instructions to theinternal and external pumps, such as device on, device off, start pump,stop pump, pump rate, volume to be infused, clear rate infused, name andconcentration of drug/solution being infused. The pumps or thecontrollers operating the pumps in turn send messages back to processor72 via the hardwired links 100 or the wired or wireless links 100existing between processor 72 and external pump controllers 32, 42 and52. The status messages returning from the pumps controllers includetypically: channel identifier, channel status, rate, dose, volumeremaining, infusion label, flow check, primary volume infused, piggybackvolume infused and volume history last cleared. Each of those messagesis known to those of skill in the art. For example, the “channel status”is a monitoring of the pump's exception status, which includesinformation such as: no exception, battery low alert, lithium batterylow alert, channel stopped alert, changing piggyback program alert,programming piggyback alert, keep vein open (“KVO”) alert, piggybackcall back alert, priming alert, dose out of range alert, batterydepleted alarm, tube not loaded alarm, tube misloaded alarm, tubeloading alarm, close regulating clamp alarm, incomplete piggybackprogram alarm, incomplete primary program alarm, piggyback out of rangealarm, primary out of range alarm, air in line alarm, downstreamocclusion alarm, upstream occlusion alarm, reset manual tube releasealarm, temperature too high alarm, temperature too low alarm and channelfailure.

As illustrated above, there exists a wealth of information that iscommunicated between control processor 72 of machine 20, the internallylocated pumps 112 to 120 and the externally located pumps 32, 42 and 52.As illustrated below, maintaining control of pumps located both insideand outside of machine 20 provides many advantages with respect to theoverall operation of the therapy. It should be appreciated that while inone preferred embodiment controller 70 and processors 72 and 74 arelocated within housing 25 of machine 20, it is also possible that suchcontrol be maintained on an external PC, on a local area network or on awide area network such as the Internet.

Referring now to FIG. 3, one possible flow schematic for the system 10is illustrated. The flow schematic shows a hybrid of the hemofiltrationand hemodialysis therapies (sometimes called hemodiafiltration). In theillustrated embodiment, system 10 operates with a hemodialyzer orhemofilter 140. Hemodialyzer or hemofilter 140 includes a blood inlet142 and a blood outlet 144. Hemodialyzer 140 also includes a dialysateinlet 146 and an ultrafiltrate outlet 148. The primary differencebetween a hemodialyzer, such as dialyzer 140, and a hemofilter is thatthe hemofilter typically has a greater porosity to allow for themovement of large quantities of plasma water across the membrane.Hemofiltration relies upon makeup fluid being added via the substitutionpumps 114 a and 114 b.

As illustrated, system 10 in FIG. 3 includes two substitution pumps 114a and 114 b. Substitution pump 114 a is a predilution pump, whichinjects substitution fluid into blood line 102 prior to the blood inlet142 of dialyzer 140. Substitution pump 114 b, on the other hand, is apostdilution pump which injects the same or different substitution fluidinto blood line 104 after the blood exit 144 of dialyzer 140. Asillustrated, predilution substitution pump 114 a pulls fluid from source148, while postdilution substitution pump 114 b pulls fluid from source150. The predilution and postdilution fluids can be the same ordifferent. The dialyzer 140 receives dialysate via pump 116 from one ormore dialysate supply 152. In a similar manner, filtration pump 118pulls ultrafiltrate through exit port 148 of dialyzer 140 to one or morean ultrafiltrate bag 154.

In FIG. 3, the anticoagulant pump 120 is a syringe-type pump which isknown in the art. The anticoagulant is pumped in a similar manner to apredilution substitution fluid into blood line 102 located upstream ofdialyzer 140. The anticoagulant can be of any suitable type, such asheparin or citrate.

External pumps 32, 42 and 52 are fluidly connected to the patient'sbloodline 104. In FIG. 3, pumps 32, 42 and 52 feed fluid to blood returnline 104. Alternatively, one or more or all of the remote administrationpumps 32, 42 or 52 fluidly communicates with the blood line 102, e.g.,prior to dialyzer 140, or with the return line 104 upstream of the airdetector 166, as shown by phantom lines leading to such upstream point.Alternatively, one or more or all of the remote administration pumps 32,42 or 52 fluid communicates directly with the patient 170 as shown byphantom lines leading to patient 170 and does not connect to bloodline102 or bloodline 104. In FIG. 3, each of the pumps controllers 32, 42and 52 is shown pulling fluid from supplies 156, 158 and 160,respectively, to return line 104. Supplies 156, 158 and 160 can includeany suitable or desirable fluid, such as heparin, citrate or otheranticoagulant, crystalloid, colloid, concentrate, an administrationfluid, an electrolyte solution, an intravenous fluid, an antibiotic, avasoactive drug, a total parenteral nutrition solution, an enteralnutrition solution fluid, fluid via feeding by mouth, fluid via feedingby tube and any combination thereof.

As discussed above, system 10 includes a number of sensors controlled bycontrol processor 72. For instance, control processor 72 monitors inputsfrom various pressure sensors 162. Further, a blood leak detector 164 isplaced in the ultrafiltrate line 106 to look for any blood cells,platelets or other desirable blood components that have improperlypassed through the walls of the membranes contained within dialyzer 140.Processor 72 also receives signals from air detector 166, which detectsair in the blood line that may return to the patient 170. If air isdetected, controller 70 immediately sends a signal to the blood pump 112and clamp 168 to stop the flow of blood to and from the patient 170.

In operation, blood pump 112 pulls blood through blood removal line 102,pumps the blood through dialyzer 140 and returns the blood to thepatient 170 via return line 104. In the process, the blood receives ananticoagulant and a predilution substitution fluid in blood withdrawalline 102. The blood is then dialyzed or cleaned by diffusion viadialysate, which is pumped outside of the membranes carrying the bloodwithin the dialyzer 140. The blood then receives more substitution fluidon the postdilution line. The remote administrate pumps 32, 42 and 52also inject certain additives into blood return line 104, blood removalline 102 and/or directly to patient.

Referring now to FIGS. 4 and 5, various screen shots of GUI 60illustrate the synchronization and calculation features of the pumpingsystem 10 of the present invention. In particular, FIG. 4 illustratesthe synchronization of the pumps, while FIG. 5 illustrates thecalculation feature of system 10. It should be appreciated that not allof the information disclosed in FIGS. 4 and 5 has to be displayed on GUI60. Further, additional information may be displayed on differentscreens in combination with the information shown in FIGS. 4 and 5 or inseparate screens on GUI 60. Still further, the system is not required tooperate with a touch screen and can alternatively or additionallyoperate with electromechanical input devices, such as knobs, pushbuttons, switches and the like.

GUI 60 of FIG. 4 illustrates that system 10 provides the MFT machine 20the ability to start and stop various pumps automatically or manuallybased on operator selectable settings for the auto-remove column 62shown on GUI 60. As illustrated, pumps 32, 52 and 54 are each selectedfor auto removal. That is, those pumps are set to automatically startand stop without any additional input from the operator. In onepreferred embodiment, GUI 60 provides an operator override to manuallyshut off a pump that is currently being controlled automatically. Forexample, areas 62 a to 62 d on GUI 60 in an embodiment are associatedwith a touch screen interface, wherein an operator can touch, forexample, input 62 a to change the state from auto-remove tono-auto-remove. The no-auto-remove state can be set to default to apump-off condition, so that changing from auto-remove to manualoperation effectively reduces an input or output total flowrate by thepump rate of the associated pump. The operator can thereafter start/stopthe pump via a separate input.

As illustrated, Pump B (element number 42) is currently running asindicated by column 58. The pump 42 is not set to auto-remove, so thatthe pump requires an external start input to initiate flow. Pump B,however, is synchronized with the filtrate pump to only run when thefiltrate pump is running, as indicated by column 64.

Column 64 indicates the pump, if any, to which the automaticallycontrolled pumps are synchronized. As illustrated, IV pumps 32 and 52are synchronized to pump when the blood pump is pumping and not pumpwhen the blood pump is not running. IV pump 42 is set to be synchronizedwith the filtrate pump, e.g., to pump when the filtrate pump is pumpingand not pump when the filtrate pump is not pumping. IV pump 54, whilebeing controlled automatically, is not tied to the flow or pumping ofany other pump. In such a case, control processor 72 can intermittentlysend a signal to start and stop IV pump 54. Inputs 64 a to 64 d enablean operator to change the pumps to which the IV pumps are synchronized.Inputs 64 a to 64 d can be toggled inputs, be selected from a displayedgroup, or enable the operator to key in the pump name from a keyboard.In an alternative embodiment, such synchronization is predetermined by aphysician and set to be locked so that the setting is not changeable.

Column 66 provides a pump identifier. Column 68 specifies the drug orother fluid that is to be injected via the external IV or administrationpump. Column 56 sets forth the desired flowrate for the drug, e.g., bysetting a flowrate amount (ml/hr) or by setting a condition, such as akeep vein open condition. Column 58 illustrates the current status ofthe particular pump. For example, pumps 42 and 52 are currently running,while pump 32 is stopped. Column 76 illustrates the IV dose for each ofthe drugs or fluids, which is a calculated value (performedautomatically by some external pumps) and is typically the drug'sconcentration per time unit and/or per patient weight. Column 78represents the percent of total flowrate of the particular drug beingpumped by pumps 32, 42, 52 and 54. Column 82 sets forth the amount offluid remaining in the supplies for pumps 32, 42, 52 and 54,respectively. Column 84 sets forth the amount of time remaining tocomplete the infusion of a particular drug via one of the pumps 32, 42,52 and 54.

FIG. 4 illustrates that one of the remote IV or administration pumps canbe tied to one of the integrally located pumps, such as the blood pump.Other remote pumps could be tied to or dependent upon the integralfiltrate pump, or to another remote pump. In a similar manner, one ofthe internally housed pumps can be tied to or dependent upon the flow ofanother one of the internally housed pumps or to the flow of a remotepump. For example, the dialysate flow could be tied to or dependent uponthe pumping of blood or vice versa.

Importantly, system 10 of MFT machine 20 commands certain remote pumpsset to be under automatic control, enabling the operator to performother tasks. Such remote control is also performed without thepossibility of being effected by human error. Safety processor 74 doublechecks to ensure that a particular IV pump is on when it is supposed tobe on and vice versa. Because the control is centralized within the MFTmachine 20, safety processor 74 can make such a determination based onthe knowledge of the flow scheme set in or programmed into software andthe feedback being provided by remote devices 30, 40 and 50.

System 10 increases accuracy and safety and reduces the amount of humaninput and attention that is needed with known systems, wherein knownsystems require the external infusion pumps to be operated independentlyfrom the main therapy machine. In known therapy systems, if the maintherapy machine is used to manage the patient's total fluid balance, thefluid balancing must be done manually by an operator adding variouspatient inputs, outputs and calculating an actual removal rate that isneeded to achieve a desired removal rate. The system 10 performs suchtotal fluid balancing automatically. Indeed, system 10 enables theoperator to simply enter the desired fluid loss or gain, wherein thesystem controls either the filtrate output, the substitution fluid inletor both to achieve the inputted loss/gain.

Additionally, system 10 looks at the input and output pumps, includingthe substitution pumps 114, the filtrate pump 118 and the anticoagulantpump 120 to determine the actual filtrate or substitution fluid rateneeded. That is, the system 10 looks at the substitution pump andanticoagulant syringe pump to see if the actual flowrate is the same,less than or more than the entered or expected flowrate. If so, system10 automatically adjusts the filtrate or additive rate to achieve thedesired loss/gain amount.

FIG. 5 illustrates the calculation feature of the present invention. InFIG. 5, the internal flowrates, such as the substitution fluid or thedialysate input are shown by rows 87 and 89. The infusion oradministration pumps A to D are represented by rows 88 to 94. The outputpumps are indicated by rows 96 and 98. The calculation feature providesa tool that simplifies operation and reduces errors in connection withsetting the prescribed patient gain or loss rate. The operator sets theIV pumps to either be automatically controlled or manually controlled,for example, via buttons 62 a to 62 d in FIG. 4. Any of theautomatically controlled pumps is thereafter controlled via system 10without operator input, except in emergency situations. In FIG. 5, theoperator enters the patient's urine output as seen in row 96, thesubstitution fluid rate, as indicated by row 87, the dialysate input asindicated by row 89 and the desired patient net gain or loss asindicated by row 86. The urine output in row 96 is alternativelymeasured and inputted via a measuring device, such as via scales 26 and28 in FIG. 1.

Column 172 describes the fluid source/pump, or in the case of row 86,the net desired gain or loss. Column 174 indicates whether theassociated external device will infuse a component into the patient ormonitor the removal of a component from the patient. Column 176indicates the flowrate for the source or output shown in column 172.Column 178 shows whether the flowrate information is automatic, e.g.,set in software, or otherwise permanently set or entered, e.g., by theoperator or via measurement and feedback from a device, such as feedbackfrom a urine measurement device. Further, the automatically enteredflowrates could be based on a predefined percentage of the net fluidloss rate or be prescribed by a physician.

Entry 182 shows the total flowrate of all the inputs from rows 87 to 94.The equation used to determine the calculated filtrate actual pump rateshown in entry 186 is:Filtrate pump rate=total input rate−total external outputrate+prescribed net loss rate.By that equation, the total input rate of nine hundred fifty ml/hr,which is the sum of all the infusion pumps (rows 88 to 94) plus thesubstitution fluid pump (row 87), is shown in entry 182. System 10automatically subtracts the calculated total output rate of two hundredml/hr shown in entry 184, which is the sum of the patient's urine outputin column 96 plus a Scale AA output shown in column 98. The total inputrate less the total external output rate is seven hundred fifty ml/hr.Scale AA it should be appreciated can be a measurement of any suitablefluid or other inputted or outputted material. For example, Scale AAcould be used to measure the patient's urine output instead of thatparameter being inputted by the operator. Adding to the seven hundredfifty ml/hr the prescribed net loss rate of three hundred ml/hraccording to the equation yields a calculated actual filtrate rate ofone thousand fifty ml/hour as shown in entry 186.

The system at the beginning of the therapy as illustrated automaticallydetermines to run filtrate pump 118 to pull one thousand fifty ml/hr toachieve the desired net loss from the patient of three hundred ml perhour based on all the other inputs and outputs shown, which can be fromsources internal and external to MFT machine 20. Display 188 shows thatan error would be generated if a negative ultrafiltrate rate would havebeen generated. Inputs 190 and 192 enable the operator to canceldisplayed values or accept the values shown, respectively. It shouldtherefore be appreciated that changing any of the amounts shown incolumn 176 for the various entries in rows 86 to 98 affects thecalculated filtrate pump rate shown in entry 186.

Data entry layouts 194 and 196 show two possible embodiments forentering values into column 176 of GUI 60. Layout 194 is a togglingsystem that enables the operator to press an up arrow to increase aninput or to decrease an output. Therefore, to decrease the prescribedloss shown in column 86, the operator presses the up arrow which movesthe loss of three hundred towards zero. The down arrow in turn moves theloss of three hundred further away from zero. That down arrow alsodecreases the inputs of rows 87 to 94 towards zero, while up arrow movesthe input values away from zero. When the operator is satisfied with thedisplay of an amount, the operator presses the enter input, which entersthe current value highlighted in the display above and moves the entrysequence to the next entry.

Input system 196, on the other hand, enables the operator to key in theamounts of the fluid gain or fluid loss and select whether the amountentered is a negative flow (or output) or a positive flow (or input) viathe plus and minus buttons. Again, when the operator is satisfied withan entry, the operator selects the enter input to move to the next row.When all the amounts are either entered or automatically generated, thenumbers displayed in entries 182 to 186 are generated. Thereafter, theoperator can change values or accept the flow values via inputs 190 and192.

The Accura™ hemodialysis/hemofiltration machine produced by the assigneeof the present invention also enables the operator to use a knob toscroll through a number of selectable options and press a dedicated“enter” or “OK” button. Such a selection option is also available foruse with the present invention to increase or decrease a fluid gain/lossby a set amount (e.g., in millimeter increments). Such a knob could alsobe used with the selectable items of FIG. 4 as well as the otherselectable features (e.g., columns 172, 174 and/or 176) of FIG. 5.

System 10 enables the operator to change values over time and thereforeset, for example, a desired loss rate during a first hour of therapy, adesired gain rate during the second hour of therapy and so on. Thefeedback via communication links 100 between the MFT machine 20 and theexternal input/output devices 30, 40 and 50 also enables the machine tocheck whether a pump is actually pumping what it has been commanded topump. If, for example, Pump B is only inputting one hundred twenty-threeml/hour versus the one hundred twenty-five entered, system 10automatically compensates for the loss of two ml/hour by varying thepump rate of the filtrate pump (or pump rate of the substitution pump).Such error checking can occur at regular intervals set by processorspeeds or via software. System 10 in that manner becomes a highlyaccurate system that achieves an ultimate goal of balancing theflowrates of the numerous pumps involved with the medical fluid therapywith little operator input.

If a certain actual flowrate falls above or below the inputted flowrateto a specified degree, the information is transmitted via wiringinternal to machine 20 or across the appropriate link 100 to controller70 of machine 20, which generates an alarm notifying the operator of aflow error condition. Moreover, if the actual flowrate does not equalthe entered flowrate but the disparity is not such that an alarmcondition is necessary, system 10 nevertheless monitors the overallflowrate of, for example, an additive to show the operator that thepatient received slightly more or less of such additive than wasprescribed. The following example also highlights some of thecapabilities of the present invention.

EXAMPLE

Patient XYZ's prescription has a net fluid removal rate of 300 ml/hr.XYZ's nurse enters into the MFT machine 20 that the patient is to have aprescribed-loss-rate of 300 ml/hr. Patient XYZ also has prescriptionsfor four administration pumps that are networked under the system 10.Patient output is measured and entered hourly. Patient XYZ's nurseenters the rates for the four pumps (e.g., Pumps A to D) directlythrough the MFT machine 20, or at one or more interfaces for theexternal devices. Patient XYZ has a urinary catheter connected to adrain bag that automatically measures the patient's urine output.Patient XYZ begins therapy and the four infusion pumps begin toadminister 460 ml/hr in total. The pumps run, nonstop, without alarm ortechnical problems. Patient XYZ's therapy machine 20 is instructed togive 2000 ml/hr of substitution fluid. Continuously and substantiallyevenly over each hour, Patient XYZ's therapy machine's filtrate pumpremoves 2000 ml+460 ml less any hourly amount reported by the urinaryoutput device.

During the second hour, the prescription changes to a net gain of 100ml/hr. The infusion administration rates are the same at 460 ml/hr. Thepatient's urinary output device reports there is no urine output. Duringthe second hour, the MFT machine 20 administers the required 2000 ml/hrof substitution fluid as prescribed and removes 2360 ml ofultrafiltrate, giving Patient XYZ, a net fluid balance of +100 ml forthe hour.

During the third hour, Patient XYZ experiences flow difficulties withthe blood in the arterial line of the MFT machine. The machine pausesdue to an extremely negative pressure in the arterial line, while theoperator discovers this is due to a kink in the line. While the bloodpump is paused, the MFT machine commands one of the infusion pumps tostop, because the operator had that pump set to “synchronize” with theblood pump. The operator removes the kink from the line, the blood pumprestarts, and the infusion pump restarts without input from theoperator. The MFT machine 20 adjusts the hourly filtrate production rateto compensate for the fluid that was not given by the infusion pumpwhile it was paused, to meet the still prescribed net fluid change rate.A suitable appropriate message informing the operator/patient of thefluid compensation is displayed.

The first hour of the above example illustrates the ease with whichinternal and external flow components are entered and calculated insystem 10. The second hour illustrates that the system is readilyadapted to change from an overall fluid withdrawal exchange to anoverall fluid netting exchange per the patient's prescribed therapy. Thethird hour illustrates how the system frees the operator to correct atherapy problem without having to worry about: (i) shutting down one ormore pumps and (ii) making up for any downtime after the problem hasbeen resolved.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope of the present invention andwithout diminishing its intended advantages. It is therefore intendedthat such changes and modifications be covered by the appended claims.

1. A medical fluid therapy method comprising the steps of: (a)establishing a communication link between a kidney dialysis/bloodtreatment machine and at least one remote pump controller; (b) using thelink to synchronize operation of at least one pump housed integrallywith the machine with at least one pump located remotely from themachine; (c) enabling an operator to enter a net fluid transfer amount;and (d) controlling the pumps to at least substantially achieve theentered amount.
 2. The medical fluid therapy method of claim 1, whereinestablishing the communication link includes configuring the machine andremoter pump controller for wired/wireless communication.
 3. The medicalfluid therapy method of claim 1, wherein establishing the communicationlink includes establishing separate individual links between the machineand a plurality of the remote pump controllers.
 4. The medical fluidtherapy method of claim 1, wherein synchronization of the operation ofthe integral and remote pumps includes the step of running one of thepumps depending upon whether the other pump is/is not running.
 5. Themedical fluid therapy method of claim 1, wherein synchronization of theoperation of the integral and remote pumps includes the step of sensinga performance of one of the pumps and adapting control of the other pumpbased on the sensed performance.
 6. The medical fluid therapy method ofclaim 5, which includes sensing the performance of the one pumpintermittently or at least substantially continuously to adapt thecontrol of the other pump.
 7. The medical fluid therapy method of claim1, wherein controlling the pumps includes the step of accounting for atleast one fluid that is inputted into a patient, at least one fluid thatis removed from the patient and at least one fluid that is recirculatedfrom and to the patient.
 8. The medical fluid therapy method of claim 1,which includes enabling the operator to enter at least one different netfluid transfer amount during the therapy and modifying the controllingof the pumps accordingly.
 9. The medical fluid therapy method of claim1, wherein controlling the pumps includes at least one step selectedfrom the group consisting of: (i) automatically controlling the externalpump based on the entered net fluid transfer amount; and (ii)calculating and displaying a flow value that the operator inputs intothe remote pump controller.
 10. The medical fluid therapy method ofclaim 1, wherein controlling the pumps includes the step of monitoringthe communication link for error conditions.
 11. The medical fluidtherapy method of claim 10, wherein the error conditions includecommunication loss, framing errors, invalid packet format, data errorsor any combination thereof.
 12. The medical fluid therapy method ofclaim 1, which includes checking the entered net fluid transfer amountto determine if it is within a safe range.
 13. The medical fluid therapymethod of claim 1, wherein controlling the pumps includes sending aninstruction to at least one of the pumps, the instruction selected fromthe group consisting of: power on, power off, start, stop, new rate,volume to be infused, clear rate infused, name of drug, concentration ofdrug and any combination thereof.
 14. The medical fluid therapy methodof claim 1, wherein controlling the pumps includes receiving a messagefrom at least one of the pumps, the message selected from the groupconsisting of: channel identifier, channel status, rate dose, volumeremaining, infusion label, flow check, primary volume infused, piggybackvolume infused, volume history last cleared and any combination thereof.15. A medical fluid therapy method comprising the steps of: configuringa kidney dialysis/blood treatment machine to perform the equation:filtrate pump rate=total input rate−total output rate+prescribed netloss rate, wherein at least one of the total input rate and the totaloutput rate includes a flowrate output of a pump located external to themachine; and controlling a filtrate pump according to the calculatedfiltrate pump rate.
 16. The method of claim 15, wherein determining atleast one of the total input rate and the total output rate includesreceiving at least one input/output flowrate that has been sensed by asensor.
 17. The method of claim 15, wherein determining at least one ofthe total input rate and the total output rate includes receiving atleast one input/output flowrate that has been inputted manually.
 18. Akidney dialysis/blood treatment machine configured and arranged toperform the steps according to claim
 15. 19. A medical fluid therapymethod comprising the steps of: configuring a kidney dialysis/bloodtreatment machine to perform the equation:filtrate pump rate=total input rate−total output rate+prescribed netloss rate, wherein at least one of the total input rate and the totaloutput rate includes a flowrate output of a pump located external to themachine; and controlling a substitution pump according to the calculatedpump rate.
 20. The method of claim 19, wherein determining at least oneof the total input rate and the total output rate includes receiving atleast one input/output flowrate that has been sensed by a sensor. 21.The method of claim 19, wherein determining at least one of the totalinput rate and the total output rate includes receiving at least oneinput/output flowrate that has been inputted manually.
 22. A kidneydialysis/blood treatment machine configured and arranged to perform thesteps according to claim
 19. 23. A renal failure therapy methodcomprising the steps of: pumping blood through a blood circuit of akidney dialysis/blood treatment machine; infusing citrate as ananticoagulant; and controlling the citrate flowrate based on the bloodflowrate automatically so that the flowrates are synchronized.
 24. Themethod of claim 23, which includes infusing citrate into the bloodcircuit or directly to the patient.
 25. The method of claim 23, whichincludes additionally controlling citrate flowrate to deliver aprescribed amount of citrate.
 26. The method of claim 23, which isperformed during a treatment selected from the group consisting of:continuous renal replacement therapy, dialysis, hemofiltration and anycombination thereof.